In this fourth part I'll examine wether or not it is advisable to pulp-ferment plums.

As you know I often can lay my hands on large quantities of plums. A friend of mine who has an orchard always gives me a call when the plums are ripe. I can pick as much as I want as they have no economical value for him. The result is each time a deliscious plum wine. You can re-read my story about harvesting plums and making plum wine in 2007 here.

In 2009 I had again an enormous amount of plums. At that time I wrote a more detailed story about harvesting plums which I can highly recommend. The tips which are described in that story can be used for many more fruit varieties and help make your wines a lot better. You can re-read that story by clicking here.

Last year the crop was destroyed by frost in spring. However I still had some plums in my freezer and sacrificed part of this batch for these experiments.

General overvieuw of the test

I was going to do the test the same way I tested applepulp.

First the plums are thawed in a large pan. A bit of sulphite is added to prevent spoiling. Next the plums are mashed with a potatomasher.

The juice that is released during thawing and mashing is measured.

Next the plums are divided in three equal parts. These parts are stored seperately in glas jars.

Jar A contains only part of the plums and part of the juice that was released just by thawing.

Jar B contains the same however a teaspoon off pectic enyzme was added.

Jar C also contains the same and here also a teaspoon off pectic enzyme is added.

The jars are then stored in a warm place (room temperature).

Next day I could clearly see that the pectic enzymes did their job.

Then some yeast is poured into jar C. No starter or other culture but just dry yeast.

I now had 3 jars each with a different contents.

Jar A only contains plums and juice that is released in a natural way.

Jar B contains plums, their juice and some pectic enzymes to break down cell structure.

Jar C contains plums, their juice, pectic enzymes and is fermenting.

This last jar was therefore not closed by the lid but covered with a cloth fastened with a rubber band so the devellopping CO2 could escape..

General observations.

I should make a few remarks about the measurements here.

The SG is (just as last time) measured with my refractometer and the acidity is measured with the wite-tile method.

As I did not use a large amount of plums and the amount of juice being released was therefore also small I could not measure SG with a hydrometer. My refractometer is at such times a great aid. It only needs just a drop of juice to make an accurate measurement. The many more advantages of the refractometer can be re-read here.

Acidity was measured with the white-tile method. Those of you that do not have experience with acidity measurements I urge to read my 5 part series about measuring acidity. All parts are important. However part number 5 describes the easiest method of measuring acidity in dark as wel as white wines. You can re-read these stories by clicking here.

Just like in the previous story about pul-fermenting apples acidity dropped in Jar A after the fourth day. Acidity dropped from 11 to 10.I guess the same thing as with the apples is going on here: some acid is drawn back into the pulp. I do not have another explanation for this.Stange however is that this phenomenon only happens in jar A, the jar without any additions.

Jar C shows a clear drop in the SG. With the apples this did not happen, but here it did.And that is more logical. Jar C is the jar where the yeast was added and therfore is fermenting. This will cause alcohol to be formed, which makes the sugar level drop.

Jar C also shows a higher raise in acidity as in jar A and B. This is probably due to CO2 forming in the juice which influences measurements.

The most important observation is off course the change in color. In fact it tells us the whole story.

Measurements.

I am not going to bother you with all the photo's I made every day of every jar. Boring and not neccessarry.

I will present you a table with the measurements just like I did in the previous story.

SG Table

Acidity measurements

Graphs.

Just for clarity I put the measurments in a graph. The figures tell all.

As extra after 5 days I made a picture of the juice out off each of the jars.

This photo tells all.

Concluding.

Well the photo told you all.

By leaving the pulp in the juice, as in jar A and B, acidity and SG will rise. However this experiment clearly shows that pulpfermentation indeed plays an important role. fermentation released a lot more color.

So we can conclude that by leaving the pulp in the juice not only acidity and SG will rise, but the color will be more intense and generally you will get a better must.